Stent for arterialization of the coronary sinus and retrograde perfusion of the myocardium

ABSTRACT

The present invention concerns a novel stent and a method for communicating oxygenated blood directly from the left ventricle to the coronary sinus to provide retrograde perfusion to the myocardium. The stent is placed substantially within the coronary sinus with its trailing end protruding into the right atrium and the leading end protruding into the left ventricle. The stent has a smaller passageway at or near the trailing (right ventricular) end and at or near the leading (left ventricle) end, and has a covering at the trailing end. The smaller passageway and the cover at the trailing end to promote retrograde flow into the venous system of the hear and specifically the myocardium of the left ventricle and to reduce a significant left-to-right shunt.

[0001] This application is a continuation-in-part of copendingapplication Ser. No. 09/796,528, filed Mar. 2, 2001.

BACKGROUND

[0002] 1. Field of Invention

[0003] The present invention relates to a stent for supplying oxygenatedblood retrogradely to the myocardium via the coronary sinus. The stentdirects blood from the left ventricle to the coronary sinus through ahole punctured through the wall of the coronary sinus and the wall ofthe left ventricle and restricting the outflow of the coronary sinusdirects that blood retrogradely.

[0004] 2. Description of Related Technology

[0005] Retrograde perfusion using the coronary sinus has long been knownfor treating end-stage heart disease. Previous methods among othersattempted to connect the aorta to the coronary sinus using a jugularvein or an internal mammary artery graft. These methods were invasive innature and required open heart surgery.

[0006] U.S. Pat. No. 5,824,071, issued to Nelson et al. in 1998,discloses an apparatus and method for providing retrograde perfusiondirectly from the left ventricle to the coronary sinus. Nelson requiresa pressure sensitive valve that prevents pressure build-up inside thecoronary sinus from rising above 60 mm Hg. Nelson, however, does notteach how such a valve may be constructed, and it is unlikely that sucha device may be introduced percutaneously.

[0007] In 2000, Patel et al. conducted experiments for percutaneousarterialization of the coronary sinus using a stent. See Patel et al.,Percutaneous Transmyocardial Intracardiac Retroperfusion Shunts:Technical Feasibility in a Canine Model, JVIR 2000, 11:382-390. Thestent employed by Patel et al., however, results in a significant shuntof oxygenating blood from the left ventricle to the right atrium(hereinafter “left-to-right shunt”). Further, although Patel recommendsusing a T or a Y shaped device, technical problems associated withaccurately delivering such a device in place render the inventiondifficult. These factors argue for a simpler device for providingretrograde perfusion to the heart via the coronary sinus.

SUMMARY OF INVENTION

[0008] It is an object of the present invention to provide a novel stentand a method for providing oxygenated blood retrogradely from the leftventricle to the heart tissue through the coronary sinus without asignificant left-to-right shunt.

[0009] In a preferred embodiment, the present invention contemplates astent having a leading end and a trailing end and having a passagewaytherethrough. After delivery, the body of the stent is expanded or selfexpands to fit securely within the coronary sinus. The leading end ofthe stent (hereinafter “leading (LV) end) is positioned in the leftventricle, and the trailing end (hereinafter “trailing (RA)end”) ispreferably positioned in the right atrium.

[0010] The stent preferably has reduced cross sectional areas or smallerpassageways (or constrictions) at or near the leading (LV) end and thetrailing (RA) end as compared to the remainder of the stent. The size ofthe passageway decreases or tapers preferably toward the leading (LV)end and toward the trailing (RA) end. Accordingly, as blood flowsthrough the small passageway of the leading (LV) end, the passagewaybroadens in cross sectional area toward the midsection of the stent anddecreases again toward the small passageway of the training (RA) end.

[0011] The smaller passageways (or constrictions) at or near the leading(LV) end and the trailing (RA) end of the stent operate to control theamount of blood flowing into and out of the coronary sinus. The size ofthe passageway of the constriction at the leading (LV) end controls theamount of inflow into the coronary sinus.

[0012] The cover surrounding the stent at the trailing (RA) end directsblood flow through the passageway at the trailing (RA) end, and the sizeof the passageway of the constriction at or near the trailing (RA) endcontrols the amount of outflow into the right atrium. They also controlthe retrograde flow of oxygenated blood to the myocardium. The stentpreferably forms a friction fit with the lumen of the coronary sinus.

[0013] The stent is expandable cross-sectionally, and preferablycompressible cross-sectionally. For example, a stent may be fit within acatheter for delivery. After percutaneous delivery into its desiredposition, the stent may self expand to form a friction fit within thecoronary sinus. If a stent does not self expand, it may be expandedusing a balloon as known in the art or other suitable mechanism. Onceexpanded, such a stent may or may not be further compressible crosssectionally. The present invention also contemplates materials wellknown in the art, including but not limited to stainless steel, nitinol,or plastic. The stent is also made of a flexible material as known inthe art that allows bending without forming a kink.

[0014] The present invention also contemplates a percutaneous method fordelivering and placing a stent of the present invention to allow bloodflow from the left ventricle to the coronary sinus. A hole puncturedpercutaneously through the wall of the coronary sinus and the wall ofthe left ventricle creates a passageway for blood flow between the leftventricle and the coronary sinus. The hole is dilated using a balloon asknown in the art. After the stent is delivered and positioned betweenthe left ventricle and the right atrium, the sheath of the catheter isremoved to expose the stent. Preferably, the stent forms a friction fitwith the interior wall of the coronary sinus as it expands. The trailing(RA) end preferably but not necessarily protrudes through the coronaryostium and extends into the right atrium. The leading (LV) end protrudesthrough the hole in the wall of the coronary sinus and the wall of theleft ventricle to extend into the left ventricle.

[0015] In the present invention, the smaller passageway and the cover ofthe trailing (RA) end restrict blood flow into the right atrium. Withthe increased pressure inside the coronary sinus, blood flows outthrough the open interstices of the stent retrogradely to perfuse themyocardium.

[0016] Some amount of blood flow into the right atrium through thecoronary ostium, however, is necessary to control the pressure in thecoronary sinus. The cross sectional area (or diameter) of the passagewayat the trailing (RA) end (or constriction) should be large enough toprevent the coronary sinus pressure from rising above a suitablepressure, preferably about 50 mm Hg, while reducing a significant amountof left-to-right shunt. A suitable pressure limit avoids damage to thevenous system draining into the coronary sinus while effectivelyproviding retrograde perfusion. An optional covering at the leading (LV)end of the stent will help direct blood through the constriction at theleading (LV) end.

[0017] Thus, the present invention overcomes the difficulty in the priorart with an elegant and simple stent that retrogradely suppliesoxygenated blood to the myocardium while decreasing the shunting ofoxygenated blood from the left ventricle to the right atrium.

BRIEF DESCRIPTION OF THE FIGURES

[0018]FIG. 1 shows a preferred embodiment of a stent having a wire-meshconstruction and the cross sectional area of the stent tapering towardthe leading (LV) end and toward the trailing (RA) end, with a coveringaround the trailing (RA) end.

[0019]FIG. 2 shows the stent of FIG. 1 in place in a schematic diagramof the human heart.

[0020]FIG. 3 shows an alternative embodiment of a stent comprising acoiled-type construction.

[0021]FIG. 4 shows an alternative embodiment of a stent having flaringends with constrictions near the trailing end and the leading end.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

[0022] A preferred embodiment of a stent contemplated in the presentinvention is illustrated in FIG. 1. An object of the invention is toprovide a novel stent 101 which may be placed percutaneously tocommunicate oxygenated blood from the left ventricle to the coronarysinus. The stent 101 generally comprises a tubular member having aleading (LV) end 105 and a trailing (RA) end 109 and having an axialpassageway therethrough.

[0023] According to the present embodiment, the stent 101 has relativelysmaller passageways or smaller cross sectional areas (or constrictions)at or near the leading (LV) end 105 and the trailing (RA) end 109 ascompared to the rest of the stent 101. Thus, the cross sectional area(or the diameter) of the stent 101 tapers toward or near the leading(LV) end 105 and the trailing (RA) end 109. The cross sectional area (ordiameter) enlarges toward the midsection of the stent 101 and decreasestoward the trailing (RA) end 109. The diameter may be constantsubstantially in the mid section of the stent. The stent 101 at thetrailing (RA) end 109 is preferably surrounded with a cover 120 made ofsuitable material. The stent 101 at the leading (LV) end may also besurrounded with a cover (not pictured).

[0024] The smaller passageway (or constricition) and the cover at thetrailing (RA) end 109 help to direct blood retrogradely and to prevent asignificant amount of left-to-right shunt. The smaller passageway of theleading end 105 controls the amount of blood entering the coronary sinusfrom the left ventricle. Increasing the size of the passageway at theleading end increases the amount of blood flow, and decreasing the sizeof the passageway decreases the amount of blood flow. As the stent 101expands to fit securely within the coronary sinus, the cover 120 directsblood flow towards the passageway at the trailing (RA) end 109. Byrestricting flow into the right atrium, the increased pressure insidethe coronary sinus promotes the blood to flow retrogradely to the hearttissue.

[0025] A number of suitable commercially available stents having thedesired characteristics may be employed in practicing the presentinvention. Generally, the stent 101 has a wire-mesh construction withone or more interstices 113. Numerous variations in wire mesh designsand weave configurations are known in the art. The stent is preferablywoven or designed to exhibit the constrictions upon expansion. In otherembodiments, open architecture stents as known in the art may beemployed. As seen in FIG. 3, the stent 401 may also have a coiledconstruction with multiple interstices 413. The stent 401 in FIG. 3 alsohas a leading (LV) end 405 and a trailing (RA) end 409, with the stent401 tapering toward the leading (LV) end 405 and toward the trailing(RA) and 409.

[0026] The stent 101 should also be made of a flexible material that canwithstand bending without kinking. The stent 101 should maintain a fluidpassageway therethrough to allow sufficient blood flow. The stent 101may be made of a variety of commercially available materials. Metallicstents as well as non-metallic stents as known in the art may be used inthe construction of the stent 101. Non-metallic stents, for example, maybe made of a suitable plastic material. In a preferred embodiment, thestent 101 is made of surgical-grade stainless steel or nitinol.

[0027] Referring now to FIG. 2, the stent 101 of FIG. 2 is positioned ina schematic diagram of the human heart 200. The heart 200 generallycomprises a left ventricle 202, a left atrium 206, a right ventricle222, and a right atrium 210. The left ventricle 202 is primarilyresponsible for delivery of oxygenated blood to the body. The leftatrium 206 receives the oxygenated blood from the lungs, which is thendelivered to the left ventricle 202. The right atrium 210 is primarilyresponsible for receiving the deoxygenated blood from the body. Thedeoxygenated blood then flows into the right ventricle 222 before beingsent to the lungs for oxygenation.

[0028] After perfusing the heart, the deoxygenated blood normally drainsthrough the coronary sinus 218 into the right atrium 210. The coronaryostium 226 separates the right atrium 210 and the coronary sinus 218.

[0029] To place the stent, a hole 220 is first punctured percutaneouslythrough the wall of the coronary sinus 218 and the wall of the leftventricle 202 under fluoroscopic control using a needle and a stiffguide. Access is preferably from the internal jugular vein but may alsobe from the femoral vein. The hole 220 is then widened using a balloonas known in the art or by some other suitable method. In a preferredembodiment, a catheter encasing the compressed stent 101 is introducedand placed into position before removing the sheath to expose the stent101. The method used by Patel et al., may be employed in delivering thestent according to the present invention. Patel et al., PercutaneousTransmyocardial Intracardiac Retroperfusion Shunts: TechnicalFeasibility in a Canine Model, JVIR 2000, 11:382-290. Patel et al.modifies the stent delivery method as described by Rösch et al. in Röschet al., Coaxial Catheter-Needle System for Transjugular Portal VeinEntrance, JVIR, Volume 4, No. 1. pp. 145-147, 1993. The stent may alsobe marked with appropriate platinum markers to aid fluoroscopicplacement.

[0030] Referring again to FIG. 1, the stent 101 preferably has variablecross sectional area or diameter along the tubular member. The diameterof the passageway at the trailing (RA) end 109 is preferably from about1 mm to about 6 mm, and more preferably from about 2 mm to about 4 mm.Likewise, the diameter of the passageway at the leading (LV) end 105 ispreferably from about 1 mm to about 6 mm, and more preferably from about2 mm to about 4 mm. The diameter increases from the leading (LV) end 105to the midsection of the stent and decreases again toward the trailing(RA) end 109. The diameter in the middle portion of the stent may alsobe constant or may vary. The largest diameter of the stent 101 ispreferably from about 6 mm to about 15 mm. The passageway therefore maytaper or constrict toward each constriction at or near each end 109 or105.

[0031] Referring now to FIG. 2, the stent 101 is positioned as follows.The stent 101 is positioned to fit substantially within the coronarysinus 218 to preferably form a friction fit. The leading (LV) end 105 ofthe stent 101 protrudes through the hole 220 and extends into the leftventricle 202. The leading (LV) end 105 extends preferably from about 2mm to about 10 mm into the left ventricle 202. The trailing (RA) end 109of the stent 101 preferably protrudes past the coronary ostium 226 intothe right atrium 210. The trailing (RA) end 109 protrudes preferablyfrom about 2 mm to about 10 mm into the right atrium 210. In otherembodiments, the trailing (RA) end may be within the coronary sinus. Anoptional cover (not shown) may also be placed around the leading (LV)end 105 to guarantee the inflow cross sectional area or to guaranteethat blood will flow through the constriction at the leading (LV) end.

[0032] As discussed, a cover 120 surrounds the stent 101 near thetrailing (RA) end 109. As blood flows toward the right atrium 210, thecover directs the blood into the stent through the passageway orconstriction at or near the trailing (RA) end 109, then to the rightatrium 210. Thus, the cover 120 helps in controlling the amount of bloodflow through the coronary ostium 226. The cover 120 is preferably madeof a number of commercially available materials, such as PET, PTFE, etc.The cover 120 preferably covers from about 0.5 cm to about 4 cm of thetrailing end 109 of the stent 101 and more preferably from about 1 cm toabout 3 cm of the trailing (RA) end 109 of the stent 101. Blood flowingfrom the left ventricle 202 into the coronary sinus 218 is also directedthrough the uncovered interstices 113 in the stent 101 to provideretrograde perfusion to the myocardium because of the increased coronarysinus pressure caused by the small passageway at the trailing (RA) end.

[0033] Blood flowing through the coronary ostium 226 is also controlledby controlling the size of the passageway or constriction at or near theleading (LV) end 105. If the flow rate through the passageway at thetrailing (RA) end 109 into the right atrium is too great, the hearttissue would not adequately be perfused and there would be a largeleft-to-right shunt. If, however, the size of the passageway at thetrailing (RA) end 109 is too small, pressure build up within thecoronary sinus 218 would damage the venous system being perfusedretrogradely. Preferably, the pressure within the coronary sinus shouldnot exceed a suitable pressure range to avoid damage to the coronarysinus venous system. For example, the pressure should not exceedapproximately 50 mm Hg. Thus, the passageway at the trailing (RA) end109 should be large enough to prevent excess pressure build up, butrestrictive enough to allow the heart to be supplied with oxygenatedblood.

[0034] Coronary sinus pressure may also be controlled by controlling theamount of blood flowing from the left ventricle 202 into the coronarysinus 218. Thus, the size of the passageway at the leading (LV) end 105may be controlled in relation to the size of the passageway at thetrailing (RA) end 109 to provide efficient retrograde perfusion of hearttissue without excessive pressure build up.

[0035] In an alternative embodiment, as seen in FIG. 4, the smallestdiameters or constrictions of the stent 501 are not at the leading (LV)end 505 and the trailing (RA) end 509, but preferably approximately 5 mmto about 2 cm from the leading (LV) end 505 and the trailing (RA) end509. Thus, the stent would have one or two flaring ends. The smallestcross sectional areas would be at constrictions 520 and 522, which arenear the leading (LV) end 505 and the trailing (RA) end 509,respectively.

[0036] In some embodiments, a stent having a constant cross sectionalarea throughout its length is constricted at or near the ends so thatthe cross sectional areas at the constrictions are limited. Suchconstrictions may be woven into the stent design or applied byconstricting material or other materials and/or mean as known in theart, e.g., using suture, band, wire, or tape. In other embodiments, thecover itself may limit the cross sectional area of the stent.

1. A stent for supplying oxygenated blood to heart tissue retrogradelythrough the coronary sinus comprising: a tubular member having a leadingend and a trailing end and a passageway therethrough, said tubularmember having one or more interstices therein, said tubular memberhaving a constriction at or near the leading end and a constriction ator near the trailing end, and said tubular member surrounded by a coverat or near the trailing end.
 2. The stent according to claim 1, whereinthe cross sectional area of the constriction at or near the trailing endcontrols the amount of blood flow into the right atrium.
 3. The stentaccording to claim 1, wherein the cross sectional area of theconstriction at or near the trailing end provides retrograde perfusionwhile maintaining an appropriate pressure within the coronary sinus 4.The stent of claim 3, wherein said appropriate pressure is approximately50 mm Hg.
 5. The stent according to claim 1, wherein the diameter of theconstriction at or near the trailing end is from about 1 mm to about 6mm.
 6. The stent according to claim 1, wherein the diameter of theconstriction at or near the trailing end is from about 2 mm to about 4mm.
 7. The stent according to claim 1, wherein the cross sectional areaof the constriction at or near the leading end controls the amount ofblood flowing into the stent.
 8. The stent according to claim 1, whereinthe diameter of the constriction at or near the leading end is fromabout 1 mm to about 6 mm.
 9. The stent according to claim 1, wherein thediameter of the constriction at or near the leading end is from about 2mm to about 5 mm.
 10. The stent according to claim 1, wherein thediameter of the constrictions at or near the leading and the trailingends are from about 1 mm to about 6 mm.
 11. The stent according to claim1, wherein the diameter of the constrictions at or near the leading andthe trailing ends are from about 2 mm to about 5 mm.
 12. The stentaccording to claim 1, wherein said tubular member expands crosssectionally.
 13. The stent according to claim 12, wherein said tubularmember compresses cross sectionally.
 14. The stent according to claim 1,wherein said tubular member is flexible to allow bending.
 15. The stentaccording to claim 1, wherein said stent has a mesh construction. 16.The stent according to claim 1, wherein said stent has a coiledconstruction.
 17. The stent according to claim 1, wherein the diameterof the stent does not exceed from about 6 mm to about 15 mm.
 18. Thestent according to claim 1, wherein said cover surrounds from about 0.5cm to about 4 cm of the tubular member at or near the trailing end. 19.The stent according to claim 1, wherein said cover surrounds from about1 cm to about 3 cm of the tubular member at or near the trailing end.20. The stent according to claim 1, wherein said stent has a coversurrounding the tubular member at or near the leading end.
 21. The stentaccording to claim 20, wherein said cover surrounds from about 0.5 cm toabout 4 cm of the tubular member at or near the leading end.
 22. Thestent according to claim 1, wherein said tubular member exhibits saidconstrictions when expanded without additional mechanism or means. 23.The stent according to claim 22, wherein said constrictions are woveninto the tubular member.
 24. The stent according to claim 1, whereinsaid constrictions are applied by a constricting material.
 25. The stentaccording to claim 1, wherein said constrictions are applied by aconstricting means.
 26. A method for directly supply oxygenated bloodfrom the left ventricle to heart tissue via the coronary sinus using astent comprising: a tubular member having a leading end and a trailingend and a passageway therethrough, said tubular member having one ormore interstices therein, said tubular member having a constriction ator near the leading end and a constriction at or near the trailing end,and said tubular member surrounded by a cover at or near the trailingend.
 27. The method according to claim 26, wherein said stent maintainsan appropriate pressure in the coronary sinus.
 28. The method accordingto claim 26, wherein said tubular member is positioned substantiallywithin the coronary sinus.
 29. The method according to claim 26, whereinthe leading end protrudes into the left ventricle.
 30. The methodaccording to claim 26, wherein the trailing end protrudes into the rightatrium.
 31. A method for directly supplying oxygenated blood from theleft ventricle to heart tissue via the coronary sinus using the stent ofclaim 1 comprising: creating a hole with the wall of the coronary sinusand the wall of the left ventricle to make an opening between the leftventricle and the coronary sinus, dilating the hole, percutaneouslydelivering and positioning the stent to provide a fluid passagewaybetween the left ventricle and the coronary sinus.